ovalbumin and Anthrax

Aluminum hydroxide is used as a vaccine adjuvant in various human vaccines. Unfortunately, despite its favorable safety profile, aluminum hydroxide can only weakly or moderately potentiate antigen-specific antibody responses. When dispersed in an aqueous solution, aluminum hydroxide forms particulates of 1-20μm. There is increasing evidence that nanoparticles around or less than 200nm as vaccine or antigen carriers have a more potent adjuvant activity than large microparticles. In the present study, we synthesized aluminum hydroxide nanoparticles of 112nm. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, we showed that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced a stronger antigen-specific antibody response than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3μm. The potent adjuvant activity of the aluminum hydroxide nanoparticles was likely related to their ability to more effectively facilitate the uptake of the antigens adsorbed on them by antigen-presenting cells. Finally, the local inflammation induced by aluminum hydroxide nanoparticles in the injection sites was milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant into nanometers represents a novel and effective approach to improve its adjuvanticity.

Topics: Adjuvants, Immunologic; Aluminum Hydroxide; Animals; Anthrax; Anthrax Vaccines; Antibody Formation; Antigens, Bacterial; Bacillus anthracis; Bacterial Toxins; Cell Line; Cells, Cultured; Female; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Nanoparticles; Ovalbumin; Particle Size; Vaccines

Anthrax toxin lethal factor (LF) in combination with anthrax toxin protective antigen (PA) was endocytosed and translocated to the cytosol of mammalian cells. Residues 1-255 of anthrax toxin lethal factor (LFn) was fused to a cytotoxic T lymphocyte (CTL) epitope of an influenza virus. For processing the toxins, PA must be cleaved into a 63-kDa fragment (PA63) by furin, which is a subtilisin-like processing endo-protease expressed by many eukaryotic cells. To test the ability of cells treated with the LFn fusion protein plus PA to deliver the epitope, CTL assay was performed. Two types of cell lines were identified, one was able to deliver CTL epitope while the other failed to efficiently deliver the epitope. To further elucidate the differences between these cells, the role of furin in these cells was examined. Disruption of the furin gene reduced its ability to deliver the CTL epitope. Furin expression in cells capable of efficiently delivering CTL epitope was quantitatively higher than in cells unable to deliver the epitope. The results suggest that furin plays a critical role in delivery of the CTL epitope of LFn fusion protein.

Topics: Animals; Anthrax; Anthrax Vaccines; Antigens, Bacterial; Antigens, Viral; Bacillus anthracis; Bacterial Toxins; Blotting, Western; Cells, Cultured; Chloroquine; Cytotoxicity, Immunologic; Epitopes, T-Lymphocyte; Female; Flow Cytometry; Furin; Gene Deletion; Gene Expression; Orthomyxoviridae; Ovalbumin; Peptide Fragments; Recombinant Fusion Proteins; RNA, Messenger; Subtilisins; T-Lymphocytes, Cytotoxic; Transfection